The invention relates to a liquid supply device for supplying machines with a liquid from a container wherein air is not drawn into the container.
Prior art includes DE 82 26 904 U1, DE 44 16 089 A1, DE 33 34 930 A1, DE 296 23 705 U1, DE 195 03 234 A1, and JP 3-246379 A.
Liquids, such as glue, ink and varnish, as well as organic detergents, should be kept in a liquid-tight manner so that they do not dry out and become unable to react with oxygen, their volatile constituents cannot evaporate, and no bacterial cultures can develop in them.
Such liquids are usually kept in containers or canisters made of polymer or metal. If the liquid is delivered from such a container using a pressure pump, air is forced into the container. As a result, the liquid can react with the oxygen in the air, volatile constituents can escape from the liquid, and the delivery rate is limited, since the containers do not withstand high air pressures from the pressure pump, or else containers made of very thick polymer material or metal are used. The use of containers with thick polymer walls or containers made of metal is expensive for their production and very expensive for their disposal (sometimes as special industrial waste) or for recycling, and the containers have a high weight. The limited pressure resistance of the containers limits the delivery pressure of the pressure pump and therefore limits the delivery rate of the liquid. This restricts the production speed of a machine being supplied with the liquid.
One preferred application of the invention relates to gluing machines. Glue that is to be applied to finished paper is fed from a container, for example a canister, in order to adhere paper sheets or paper webs together. Instead of paper, use can also be made of films in the form of sheets (leaves) or endless webs of polymer, metal, cork or another metal.
Another preferred application of the invention is in a coating machine for coating carrier material with a coating material. The carrier material is preferably paper in the form of paper sheets or paper webs. Films in the form of sheets or webs of polymer, metal, cork or another metal can also be coated. The coating material is preferably ink or varnish.
A further preferred application for the invention is machines or apparatus for moistening finished paper, in order to achieve a desired moisture content and to keep that content at a predetermined value or within a predetermined value range. This is done, for example, by using so-called softening liquid, which can be water, to make paper easier to crease in order that it does not tear in folding. Softening liquid may particularly be commercially available folding-aid concentrate, which is a mixture of water and additives, for example vinegar and/or washing-up liquid.
A further preferred application for the invention is printing machines, particularly sheet-fed printing machines and web-fed printing machines, and more particularly offset printing machines. Offset printing machines use so-called dampening solution to form ink-repellent regions on a printing plate cylinder. The dampening solution consists of water, alcohol or alcohol substitute and so-called additives. According to the invention, these liquid additives can be delivered from an airtight supply container to a dampening-solution preparation trough on the printing machine, without the additive coming into contact with air. This prevents an organic additive being infected by bacteria or fungi or being able to react with oxygen.
In the prior art, the liquid is forced out of the container by a pressure pump. This has the disadvantage that, at too high a delivery pressure, there is the risk that the container will burst. In addition, there is the risk that the compressed air from the pressure pump will react chemically with the liquid, or that bacteria or fungi might develop in the liquid.
It is also already known to suck liquid from a dimensionally stable canister with a suction pump. However, this has the disadvantages that either a vacuum that counteracts the pump suction force is formed in the dimensionally stable canister or the canister has to be vented. This leads to contact between the liquid and air or oxygen. The abovementioned disadvantages cause the liquid to dry out, or it may react with oxygen and/or bacteria or fungi may form in the liquid or in the canister. The same disadvantage as when the canister is vented also results if pressure pumps are used, because of the air delivered into the canister by the pumps.
The invention has the object of providing one possibility for delivering any desired quantities of liquid from the container while the outlay for material, the weight and the costs for the container and container disposal or recycling can be reduced, and contact between the liquid in the container and air or other gases can be avoided.
According to the invention, this object is achieved by a container according to the invention. At least one wall, and preferably all of the walls of the container are designed so that they can be deformed or deflected by the suction force of the suction pump which delivers the liquid and, at the same time, the container walls can be moved toward each other, without requiring the suction force of the suction pump to be significantly higher than that suction required for sucking the liquid out of an open container.
For this purpose, the container walls can be dimensionally unstable, e.g., the walls have either no stiffness or a stiffness that is so low that the walls can be bent easily and cannot stand upright independently without bending over, folding over or folding in on themselves.
According to another preferred embodiment, the walls of the container are dimensionally stable, but can be deformed plastically even by a low suction force applied by the suction pump. This means that following their plastic deformation, the container walls maintain their now deformed shape when the deformation producing forces are reduced.
Preferred fields of application of the invention are for gluing machines, coating machines and printing machines. In gluing machines and coating machines, the liquid is applied to a carrier in the form of finished paper or film. It is possible for the film to be metal, polymer, cork or another material.
According to another field of application of the invention, the liquid is a moistening liquid, for example water, for moistening finished paper in order that it can subsequently be creased more easily or can be folded in a folder without the paper tearing.
Furthermore, the invention can be used for offset printing machines, in order to feed liquid additive from a collapsible container to a mixing container, in which the additive is mixed with water and alcohol or an alcohol substitute in order to form dampening solution, which is fed to a printing plate cylinder to form ink-repellent regions. The dampening solution can also be fed to cylinders or rollers of the printing machine, for example paper guide rolls and cooling rolls, in order to prevent or to remove contamination, for example deposits of printing ink.